The present invention relates to buoyant rope assemblies, and particularly, though not exclusively, to buoyant rope assemblies for use in mooring.
Known flotation systems for single point mooring (SPM) hawsers generally take the form of a number of discrete floats laced or slid onto the rope. Such systems allow the hawser to remain flexible because of the relatively large separation between the floats, but do have problems. For example, bending tends to be concentrated in the portions of the rope between the floats, which can lead to premature fatigue of these portions. Also, the changing cross-section of the rope/float assembly can lead to snagging.
Rope assemblies are also known in which a central rope is surrounded by a buoyant layer of closed cell foam extending along the full length of the rope, with a protective outer layer thereabout. These assemblies reduce the problem of snagging and premature fatigue mentioned above, but have other problems. For example, the relative inflexibility of the assembly can lead to buckling and compression of the foam when the rope is severely bent, such as during reeling or packing. Also, the foam layer tends to stretch less than the central rope to which it is attached, and this can lead to cracking and/or separation of the foam. If cracking does not occur, the mismatch in extension may result in crushing of the foam, thereby reducing buoyancy. Further, a hawser generally experiences continually fluctuating loads due to wave action, and this cyclic loading can induce heat build-up in the rope, which is detrimental to performance and durability. The foam layer can act as an insulator and can prevent this heat from dissipating.